1. Field of the Invention
The present invention relates to a semiconductor light receiving element, more specifically, to a semiconductor light receiving element having a buried mesa structure.
2. Background Art
Generally, the types of semiconductor light receiving elements are roughly classified into a mesa type and a planar type. Among these, although the mesa type had advantage of simple manufacturing process, it had disadvantage of dark current, particularly high surface leakage current and low reliability, because electric fields readily concentrate in the periphery of p-n junction, and minute current paths are easily formed by the surface levels or surface defects formed on the exposed surface. On the other hand, although the planar type had advantage of low dark current and high reliability, because p-n junction is formed in crystals, and the part appeared on the surface has low electric fields, it had disadvantage of a complicated manufacturing process.
As a technique to eliminate disadvantages described above, a structure wherein a burying layer formed on a high-resistance semiconductor crystals containing an adequate concentration of an impurity is formed around a mesa including a p-n junction on a substrate, and the p-n junction is covered by the burying layer to reduce the surface level and the surface defect and lower the surface leakage current has been proposed (for example, refer to Japanese Patent Application Laid-Open No. 6-232442 and Japanese Patent Application Laid-Open No. 2002-324911).